| The main objective of this research was to analysis the change of maize root quality and yield in high density and study the effect of chemical regulation techniques on root quality and yield. Two genotype maize varieties,jingdan28 and xianyu335 were used to elucidate the effect of planting density (45000 plants·ha-1, 56250 plants·ha-1, 67500 plants·ha-1,78750 plants·ha-1 and 90000plants·ha-1) and Synthetic plant growth regulators(ECK) on the root quality of maize .Treatments were arranged in a split-plot design, chemical regulation was the main-plot and plant population density the subplot. The experiment was carried out to study the dynamic changes of Root morphology character, physiological character, mechanical character,hormone character and yield. And the main results were as follows:(1) The yield of xianyu335 and Jingdan28 performance single peak curve as density intensified. The highest grain yield of two hybrids was obtained from 56250 plants·ha-1 in 2009, but in 2010,the highest grain yield of jingdan28 and xianyu335 was obtained from 78750 and 56250 plants·ha-1 respective.The yield of jingdan28 and xianyu335 can be described by Quadratic equation , the order of dense planting hybrid was jingdan28> xianyu335.The yield components of spring maize were weak as plant density intensified. The experiment showed that the no ear rate,Moisture content and rare top were decrease , the 100-kernels dry weight , kernels number and plant yield were increased, The highest grain yield of jingdan28 and xianyu335were obtained from 90000 plants·ha-1 in 2009～2010.(2) With density increasing , the morphology character ( Root number ,dry weight, fresh weight, root length, volume and surface area )of roots in spring maize were declined. ECK treatment can improve the root system character of spring maize in high density and when maturing stage all indexes still keep sustainable value.(3) The research indicated that root vigor in 0-10cm depth soil showed highest activities in all soil layer. Root vigor root and total vigor in four soil layer , bleeding Intensity, all of they performanced single peak curve while growth period in different planting density and were decreased with planting density increase, ECK treatment can increase the root vigor and bleeding sap of spring maize in high density.(4) Protective enzyme( SOD, POD and CAT) performanced single peak curve while growth period in different planting density, the protective enzyme activity in 0-10cm depth soil layer were higher than others soil layer , all of them decreased as density intensifies. The content of MDA was increase gradually with the passing of growth period and increased in high density. The research indicated the activity of Protective enzyme was improved by chemical regulation , whereas the content of MDA declined. The result showed ECK can improve root physiological activity and against the effects of abiotic and biotic stresses.(5) The Experiments is conducted for in-situ measuring the tensile force of maize roots system in 5cm depth with the self-designed Root tensile tester. The result was revealed that with the density increasing, maize roots number and different layer roots number were deceased, the fifth layer to seventh layer ware significant different. While tensile force,tensile strength , fracture surface diameter and others character were deceased, the roots opening angle was not change significantly. The experiment showed that roots strength features was significantly improved by foliage spray of ECK(Ethylene-chlormequat chloride- potassium)at the 6 leaves expended stage of maize.(6) The research indicate that: With the density intensified , the flow rate of hormone(IAA, Z+ZR, DHZ+DHZR,iP+iPA,GA4 and ABA)was decreased .ECK improve all content of hormones in bleeding sap.In the meanwhile ,with the density intensified , the content of hormone(IAA, Z+ZR, DHZ+DHZR,iP+iPA and GA4)in root of spring maize was decreased, the content of ABA was increased, .ECK improve all content of hormones in roots but ABA .(7) The height and the ear height of the spring maize was increased with density intensified, stem diameter, Dry Matter Accumulation in Above-ground and root shoot ratio were decreased. The effects of ECK can lower the height and the ear height of jingdan28 and xianyu335 in the high density, increasing stem diameter, Dry Matter Accumulation in Above-ground and root shoot ratio. |
PDF Full Text Request